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D R Headon

Publications and source records attributed to D R Headon.

At least 19 recordsLinked to original sources
PubMed2002

Lactoferrin: influences on Langerhans cells, epidermal cytokines, and cutaneous inflammation.

It has been suggested previously that, in addition to other biological roles, lactoferrin (LF) may display antiinflammatory properties secondary to the regulation of cytokine expression. To explore this concept further, we have here examined in human volunteers the influence of recombinant homologous LF on the migration of epidermal Langerhans cells (LC), a process that is known to be dependent upon the local availability of certain proinflammatory cytokines including tumor necrosis factor alpha (TNF-alpha) and interleukin 1beta (IL-1beta). In common with previous studies in mice, it was found that topical administration of LF prior to exposure at the same site to the contact sensitizer diphenylcyclopropenone resulted in a significant reduction of allergen-induced LC migration from the epidermis (measured as a function of the frequency of CD1a+ or HLA-DR+ LC found in epidermal sheets prepared from punch biopsies of the treated skin sites). However, under the same conditions of exposure, LF was unable to influence migration of LC induced by the intradermal administration of TNF-alpha data consistent with the hypothesis that one action of LF in the skin is to regulate the local production of this cytokine. Further support for this hypothesis was derived from experiments conducted with IL-1beta. This cytokine is also able to induce the mobilization of LC following intradermal injection, although in this case, migration is known to be dependent upon the de novo production of TNF-alpha. We observed that prior exposure to LF resulted in a substantial inhibition of IL-1beta-induced LC migration, data again consistent with the regulation of TNF-alpha production by LF. Collectively, these results support the view that LF is able to influence cutaneous immune and inflammatory processes secondary to regulation of the production of TNF-alpha and possibly other cytokines.

Administration, Topical↗
PubMed2001

Exogenous topical lactoferrin inhibits allergen-induced Langerhans cell migration and cutaneous inflammation in humans.

BACKGROUND: Lactoferrin (LF), an iron-binding protein found in exocrine secretions, is known to possess antibacterial properties. It has recently been proposed that LF may also influence inflammatory reactions. OBJECTIVES: To characterize in humans the ability of recombinant homologous LF to inhibit the induced migration of epidermal Langerhans cells (LCs) from the skin, a process known to be dependent upon the proinflammatory cytokines tumour necrosis factor (TNF)-alpha and interleukin 1beta and to influence cutaneous inflammatory reactions. METHODS: We investigated the anti-inflammatory properties of LF in human volunteers. RESULTS: Topical exposure to LF 2 h prior to sensitization caused a significant reduction in contact allergen (diphenylcyclopropenone, DPC)-induced LC migration from the epidermis as judged by the altered frequency of cells expressing either HLA-DR or CD1a determinants. That this reduction was secondary to an inhibition of TNF-alpha production was indicated by the fact that LF failed to influence LC migration induced by intradermal injection of this cytokine. In approximately 50% of those volunteers who displayed local inflammation in response to DPC, LF was found to cause a discernible reduction in the clinical severity of the reaction, associated with reduced infiltration of inflammatory cells. CONCLUSIONS: These data demonstrate that LF is able to influence cutaneous immune and inflammatory responses, possibly because of an impaired production of local proinflammatory cytokines.

Adult↗
PubMed2001

Lactoferrin protects neonatal rats from gut-related systemic infection.

Lactoferrin is a milk protein that reportedly protects infants from gut-related, systemic infection. Proof for this concept is limited and was addressed during in vivo and in vitro studies. Neonatal rats pretreated orally with recombinant human lactoferrin (rh-LF) had less bacteremia and lower disease severity scores (P < 0.001) after intestinal infection with Escherichia coli. Control animals had 1,000-fold more colony-forming units of E. coli per milliliter of blood than treated animals (P < 0.001). Liver cultures from control animals had a twofold increase in bacterial counts compared with cultures from rh-LF-treated pups (P < 0.02). Oral therapy with rh-LF + FeSO(4) did not alter the protective effect. In vitro studies confirmed that rh-LF interacted with the infecting bacterium and rat macrophages. An in vitro assay showed that rh-LF did not kill E. coli, but a combination of rh-LF + lysozyme was microbicidal. In vitro studies showed that rat macrophages released escalating amounts of nitric oxide and tumor necrosis factor-alpha when stimulated with increasing concentrations of rh-LF. The in vitro studies suggest that rh-LF may act with other "natural peptide antibiotics" or may prime macrophages to kill E. coli in vivo.

Animals↗
PubMed2000

Regulation of epidermal Langerhans cell migration by lactoferrin.

Lactoferrin (LF) is a member of the transferrin family of iron-binding glycoproteins to which several anti-inflammatory functions have been ascribed. LF has been shown to down-regulate expression of the pro-inflammatory cytokine tumour necrosis factor-alpha (TNF-alpha), although the possibility has been raised that the activity of LF in this regard was indirect and secondary to its ability to bind to and inactivate the bacterial lipopolysaccharide (LPS) used to induce cytokine production. However, the identification of putative membrane receptors for LF raises the possibility that the interaction of LF with its receptor may be one important route through which this protein exerts anti-inflammatory activity. In the present investigations the biological properties of LF have been examined in a model of cutaneous immune function where the allergen-induced migration of epidermal Langerhans cells (LC) from the skin and their subsequent accumulation as dendritic cells (DC) in skin-draining lymph nodes are known to be dependent upon the de novo synthesis of TNF-alpha, but independent of exogenous LPS. Consistent with the protein having direct anti-inflammatory properties, it was found that the intradermal injection of recombinant murine LF (either iron-saturated or iron-depleted LF) inhibited significantly allergen (oxazolone) -induced LC migration and DC accumulation. That these inhibitory effects were secondary to the inhibition of local TNF-alpha synthesis was suggested by the findings that first, LF was unable to inhibit LC migration induced by intradermal injection of TNF-alpha itself, and second, that migration stimulated by local administration of another epidermal cytokine, interleukin 1beta, which is also dependent upon TNF-alpha production, was impaired significantly by prior treatment with LF. Finally, immunohistochemical analyses demonstrated the presence of LF in skin, associated primarily with keratinocytes. Collectively these data support the possession by LF of direct immunomodulatory and/or anti-inflammatory activity, probably associated in this case with inhibition of cytokine production. Furthermore, the results suggest that as a constituent of normal skin, LF may play a role in homeostatic regulation of cutaneous immune function.

Allergens↗
PubMed2000

Recombinant human lactoferrin is effective in the treatment of Helicobacter felis-infected mice.

Recombinant human lactoferrin possesses in-vitro antibiotic and anti-inflammatory activity similar to the native form. It was tested for in-vivo activity in mice infected with the gastritis-inducing bacterium Helicobacter felis. A two-week course of treatment with lactoferrin was sufficient to partially reverse both infection-induced gastritis and the infection rate, and fully reverse gastric surface hydrophobicity changes. A comparison of lactoferrin with amoxicillin and standard triple therapy revealed no differences in infection rate. These results show that recombinant human lactoferrin is effective in a mouse model of Helicobacter infection, and support further testing of this promising agent for this application.

Amoxicillin↗
PubMed1999

Novel therapies for Helicobacter pylori infection.

BACKGROUND: Increasing antibiotic resistance has begun to impair our ability to cure Helicobacter pylori infection. AIM: To evaluate orally administered novel therapies for the treatment of H. pylori infection. METHODS: Healthy H. pylori infected volunteers received: (a) hyperimmune bovine colostral immune globulins, (b) an oligosaccharide containing an H. pylori adhesion target, Neu5Aca2-3Galb1-4Glc-(3'-sialyllactose), or (c) recombinant human lactoferrin. Outcome was assessed by urea breath test or histological assessment of the number of H. pylori present. RESULTS: None of the novel therapies appeared effective and no adverse events occurred. CONCLUSION: Although in vitro data appeared promising, in vivo results were disappointing. Higher doses, longer duration of therapy, adjunctive acid suppression, or a combination could possibly yield better results.

Adjuvants, Immunologic↗
PubMed1995

Ovarian carcinoma-associated TaqI restriction fragment length polymorphism in intron G of the progesterone receptor gene is due to an Alu sequence insertion.

Alu sequences, short, repetitive transposable DNA elements, are factors in a number of genetic diseases. We previously identified a germline TaqI RFLP, located in intron G of the human progesterone receptor gene, that showed an association with the incidence of sporadic ovarian carcinoma. Furthermore, the polymorphism was characterized as a small (approximately 300-bp) insertion that was inherited in a Mendelian fashion. Because of its insertional character, we named this polymorphism PROGINS. We report the identification of PROGINS as a 306-bp Alu element of the PV or HS-1 Alu subfamily.

Alleles↗
PubMed1995

Molecular cloning, expression and evaluation of phosphohydrolases for phytate-degrading activity.

Four acid phosphatase (phosphomonoesterase E.C.3.1.3.2) genes were cloned by polymerase chain reaction (PCR). These were pho3, pho5 and pho11 from Saccharomyces cerevisiae and the gene for a phosphate-respressible acid phosphatase from Aspergillus niger. The individual genes were subcloned into an A. oryzae expression vector downstream from a starch-inducible alpha-amylase promoter and the resulting expression constructs were transformed into a mutant strain of A. oryzae, AO7. Southern hybridization analysis confirmed that the acid phosphatase genes had been integrated into the host genome with estimates of integrated copy numbers ranging from 2 to 20 for individual transformants. Northern hybridization analysis of total RNA from individual transformants revealed the presence of a single transcript of the expected size of 1.8 kb. Production of recombinant protein was induced by the addition of 30 g L-1 of soluble starch in the fermentation media. Active acid phosphatases, not present in control cultures, were detected in the supernatant fractions of transformant cultures by acid phosphatase activity staining of non-denaturing polyacrylamide gels. The ability of the recombinant acid phosphatases to hydrolyze phytate was assessed by referenced phytase (myoinositol hexakisphosphate phosphohydrolase E.C. 3.1.3.8) activity assay procedures. A two- to six-fold increase in phytase activity was measured in transformants compared to control, untransformed A. oryzae. Sufficient quantities of A. niger and pho5 recombinant acid phosphatases were generated from large-scale fermentations to assess the efficacy of these enzymes as phytate-degrading enzymes when included in poultry diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗
PubMed1995

A germline TaqI restriction fragment length polymorphism in the progesterone receptor gene in ovarian carcinoma.

Clinical outcome in ovarian carcinoma is predicted by progesterone receptor status, indicating an endocrine aspect to this disease. Peripheral leucocyte genomic DNAs were obtained from 41 patients with primary ovarian carcinoma and 83 controls from Ireland, as well as from 26 primary ovarian carcinoma patients and 101 controls in Germany. Southern analysis using a human progesterone receptor (hPR) cDNA probe identified a germline TaqI restriction fragment length polymorphism (RFLP) defined by two alleles: T1, represented by a 2.7 kb fragment; and T2, represented by a 1.9 kb fragment and characterised by an additional TaqI restriction site with respect to T1. An over-representation of T2 in ovarian cancer patients compared with controls in the pooled Irish/German population (P < 0.025) was observed. A difference (P < 0.02) in the distribution of the RFLP genotypes between Irish and German control populations was also observed. The allele distributions could not be shown to differ significantly from Hardy-Weinberg distribution in any subgroup. Using hPR cDNA region-specific probes, the extra TaqI restriction site was mapped to intron G of the hPR gene.

Alleles↗
PubMed1995

Technical note: detection and quantification of supplemental fungal beta-glucanase activity in animal feed.

Selected hydrolytic enzymes are added to animal feeds in order to degrade specific antinutritional factors and(or) to increase availability of certain components of feedstuffs to the animal. A method is described that allows detection and quantification of beta-glucanase activity in complex feedstuffs. The method is based on radial diffusion of an enzyme-containing feed extract through an agar gel in which lichenan substrate (a relatively inexpensive glucan of mixed beta 1-->4 and beta 1-->3 linkages) has been dissolved. A linear relationship between the diameter of the zone of substrate hydrolyzed and the log of enzyme activity present was observed. The assay described is technically straightforward and requires no specialized equipment. At typical commercial inclusion levels (1 kg/t), the activity of a supplemental beta-glucanase, added to feed in a commercial mill was determined by averaging several measurements, with a precision of +/- 4%, variation between individual readings of +/- 11.3% (SD), and recovery of 109%. By using high-concentration feed extracts, the method was sensitive enough to detect background and(or) supplemental beta-glucanase activities as low as .05 kg/t supplement equivalent. This method allows consumers, producers, and regulatory authorities to measure the activity of beta-glucanase in feed at commercial inclusion levels and, hence, study the effects of processes such as pelleting and extrusion on such supplements.

Animal Feed↗
PubMed1994

The industrial production of enzymes.

The production of enzymes is a pursuit central to the modern biotechnology industry. Markets for traditional industrial enzymes continue to grow while the continued emphasis on biotechnological endeavours has generated demand for an ever increasing number of additional biocatalysts. The advent of genetic engineering has now facilitated the large-scale production of enzymes and other proteins which are produced naturally only in minute quantities. This development is particularly significant with regard to the production of enzymes and other proteins of therapeutic significance, which are now available in clinically useful quantities.The level of downstream processing to which any enzyme is subjected is dependent upon its intended application. Industrial enzymes produced in bulk generally require little downstream processing, and hence are relatively crude preparations. Enzymes destined for therapeutic applications are subject to a far higher degree of downstream processing, often incorporating 3-4 chromatographic steps. While enzymology is one of the longest established branches of the biochemical sciences, it continues to be an area of ongoing, active research. The continual discovery of new enzymes and a greater understanding of previously discovered enzymes and their functional significance suggests many novel applications for these catalytic activities. The intestinal production and utilization of enzymes will continue to be of central importance in the biotechnology industry.

Journal Article↗
PubMed1994

Pediocin A, a bacteriocin produced by Pediococcus pentosaceus FBB61.

Pediocin A, a bacteriocin produced by Pediococcus pentosaceus FBB61, was purified and partially characterized. The purification was achieved by dialysis against PEG 20,000, butanol extraction and electroendosmotic preparative electrophoresis. The protocol led to a 7843-fold increase in the specific activity, with 3.9% activity recovered. SDS-PAGE of pediocin A resulted in a single 80 kDa protein band. The antimicrobial compound was sensitive to proteolytic enzymes and heat (10 min at 100 degrees C). It exhibited inhibition against species of Lactobacillus, Lactococcus, Leuconostoc, Pediococcus, Staphylococcus, Enterococcus, Listeria and Clostridium.

Bacteriocins↗
PubMed1993

An ultrafiltration method for the removal of interfering agents and its application to the determination of free ammonia in solutions of oxystarch by the Berthelot reaction method.

Oxystarch was chosen as a model compound for studying biological ammonia-sequestering systems. Ammonia was determined by use of an ion-selective electrode, by L-glutamate dehydrogenase (L-GDH), and by two different Berthelot procedures, in the presence and absence of oxystarch. In the presence of total oxystarch the Berthelot method, particularly when low concentration reagents were used, detected significantly less (P < 0.10) free ammonia than either L-GDH or ion-selective electrode methods. A 0.5-kDa molecular weight cutoff sample ultrafiltration step was added prior to analysis by L-GDH and Berthelot procedures. To facilitate complete removal of oxystarch by the ultrafiltration step, oxystarch was dialyzed before use, yielding a high-molecular-weight fraction (> 1 kDa). Removal of high-molecular-weight oxystarch species and bound ammonia by ultrafiltration of samples prior to assay completely negated discrepancies between ammonia levels measured by L-GDH and both Berthelot methods. The correlation of the levels of measured ammonia, as determined by L-GDH and Berthelot methods, in mixtures with high-molecular-weight oxystarch was significantly improved by the addition of the sample ultrafiltration step. Improved correlation of results from such fundamentally different methods demonstrates the removal of interfering agents as well as the nonperturbatory nature of the improved procedure. The addition of such an ultrafiltration step may be applied to the determination of ammonia by the otherwise interference-prone Berthelot assay in mixtures with any interfering macromolecules, without the inconvenience or potential variabilities associated with distillation or diffusion procedures.

Ammonia↗